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Giovanna Palermo, Luca Barberi, Giovanni Perotto, Roberto Caputo, Luciano De Sio, Cesare Umeton, Fiorenzo G Omenetto
The use of biomaterials as optical components has recently attracted attention because of their ease of functionalization and fabrication, along with their potential use when integrated with biological materials. We present here an observation of the optical properties of a silk-azobenzene material (Azosilk) and demonstrate the operation of an Azosilk/PDMS composite structure that serves as a conformable and switchable optical diffractive structure. Characterization of thermal and isomeric properties of the device, along with its overall performance, is presented in terms of diffractive characteristics and response times...
August 18, 2017: ACS Applied Materials & Interfaces
Chenxiao Xiong, Meiran Xie, Ruyi Sun
The synthesis and characterization of a linear supramolecular polymer formed by dual host-guest recognitions is presented. The polymer linked by the orthogonal interactions of azobenzene with β-cyclodextrin and methyl viologen with sulfonatocalix[4]arene is constructed, and the morphology change along with the formation and vanishment of host-guest interaction is investigated. The reversible disassembly-reassembly of the polymer induced by light and the redox process are monitored by UV-vis and cyclic voltammetry, respectively...
August 16, 2017: Macromolecular Rapid Communications
Yue Sun, Junkai Ma, Fan Zhang, Fei Zhu, Yuxiao Mei, Lu Liu, Demei Tian, Haibing Li
The light-controlled gating of ion transport across membranes is central to nature (e.g., in protein channels). Herein, inspired by channelrhodopsins, we introduce a facile non-covalent approach towards light-responsive biomimetic channelrhodopsin nanochannels using host-guest interactions between a negative pillararene host and a positive azobenzene guest. By switching between threading and dethreading states with alternating visible and UV light irradiation, the functional channels can be flexible to regulate the inner surface charge of the channels, which in turn was exploited to achieve different forms of ion transport, for instance, cation-selective transport and anion-selective transport...
August 15, 2017: Nature Communications
Christopher Weber, Linus Pithan, Anton Zykov, Sebastian Bommel, Francesco Carla, Roberto Felici, Christopher Knie, David Bléger, Stefan Kowarik
Functional materials that exhibit photoinduced structural phase transitions are highly interesting for applications in optomechanics and mechanochemistry. It is, however, still not fully understood how photochemical reactions, which are often accompanied by molecular motion, proceed in confined and crystalline environments. Here we show that thin films of azobenzene trimers exhibit high structural order and determine the crystallographic unit cell. We demonstrate that the thin film can be switched partially reversibly between a crystalline and an amorphous phase...
August 15, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Stefano Luigi Luigi Oscurato, Fabio Borbone, Pasqualino Maddalena, Antonio Ambrosio
The directional light-induced mass migration phenomenon arising in the photo-responsive azobenzene-containing materials has become an increasingly used approach for the fabrication of controlled tridimensional superficial textures. In the present work we demonstrate the tailoring of the superficial wettability of an azopolymer by means of the light-driven reconfiguration of an array of imprinted micro-pillars. Few simple illumination parameters are controlled to induce non-trivial wetting effects. Wetting anisotropy with controlled directionality, uni-directional spreading and even polarization-intensity driven two-dimensional paths for wetting anisotropy are obtained starting from a single pristine pillar geometry...
August 14, 2017: ACS Applied Materials & Interfaces
Katia G Samper, Sierra C Marker, Pau Bayón, Samantha N MacMillan, Ivan Keresztes, Òscar Palacios, Justin J Wilson
The syntheses of three platinum(II) complexes bearing sulfonamide-((E)-2-(4-methylphenylsulfonamido)-2',6'-difluoroazobenzene, HL1) and hydroxy-azo-2,6-difluorobenzene ((E)-2-((2,6-difluorophenyl)diazenyl)phenol, HL2) bidentate ligands is described. These complexes, [Pt(L1)(DMSO)Cl] (1), [Pt(L2)(DMSO)Cl] (2), and [Pt(L2)2] (3), were characterized by multinuclear NMR spectroscopy, mass spectrometry, and X-ray crystallography. Despite bearing azobenzene functional groups, none of the three complexes undergo photoisomerization...
August 8, 2017: Journal of Inorganic Biochemistry
Fu-Na Meng, Zi-Yuan Li, Yi-Lun Ying, Shao-Chuang Liu, Junji Zhang, Yi-Tao Long
Herein, the structural stability of single azobenzene modified DNA duplexes, including the trans form and cis form, has been examined separately based on their distinguishable unzipping kinetics from the mixture by an α-hemolysin nanopore. Furthermore, the accurate isomerization efficiency between the trans and cis form was obtained with single molecule resolution.
August 10, 2017: Chemical Communications: Chem Comm
Quan Liu, Yuanyuan Zhan, Jia Wei, Wei Ji, Wei Hu, Yanlei Yu
Crosslinked liquid crystal polymers (CLCPs) containing azobenzene mesogens have been developed as stimuli-responsive materials, which can undergo photodeformation and thus convert light energy into mechanical force. The deformation behavior of CLCPs is strongly influenced by the alignment of the mesogens; however, a precise control of the alignment domain at micro-scale is still a challenge. Here we report complex molecular alignment in the CLCP film by using photoalignment technology. First, azo dye SD1 is aligned in-plane by UV light with a discrete alternating striped director profile...
August 10, 2017: Soft Matter
Dong Yang, Li Zhang, Lu Yin, Yin Zhao, Wei Zhang, Minghua Liu
Helical polymers are widely found in nature and synthetic functional materials. Although a number of elaborate strategies have been developed to endow polymers with helicity through either covalent bonds or supramolecular techniques, it still remains a challenge to get the desired helical polymers with controlled handedness in an easy but effective manner. In this study, we report an easily accessible gelation-guided self-assembly system where the chirality of a gelator can be easily transferred to an achiral azobenzene-containing polymer during gelation...
August 9, 2017: Soft Matter
Sergey Yu Grebenkin, Arkadiy B Meshalkin
Irradiation with linearly polarized light of azobenzene-containing polymeric matrixes causes reorientation of azobenzene molecules. In this study, the optical light-induced anisotropy of amorphous poly(alkyl methacrylates) (PAMAs) doped with an azo compound was measured at different temperatures and at two irradiation wavelengths. To describe a decrease in the efficiency of anisotropy formation with temperature, a model of molecule reorientation is suggested which includes the probability of molecule reorientation per one isomerization as a basic parameter...
August 7, 2017: Journal of Physical Chemistry. B
Melby Johny, Kanchustambham Vijayalakshmi, Ankita Das, Palas Roy, Aseem Mishra, Jyotishman Dasgupta
Synthetic control of peptide-based supramolecular assemblies can provide molecular cues to understand protein aggregation while also inspiring the development of novel chemical biology tools to deliver cargoes inside cells. Here we show that the trans-to-cis photoisomerization of a pendant azo-group covalently attached to a Phe-Phe dipeptide can comprehensively 'turn-off' its native fibrillation propensity as well as provide an optical handle to reversibly switch the aggregate morphology from fibril to vesicle...
August 17, 2017: Chemical Communications: Chem Comm
Wenpeng Yang, Ke Wu, Weimin Yang, Hailing Wang, Xianglong Lv, Lihua Qian, Tianshui Yu, Zengquan Li, Xiangji Zhou, Godfrey Okumu Barasa, S L Yuan, Yingtao Jiang, Zhilin Yang
Nanoporous noble metals and alloys are widely utilized as efficient catalysts, because they have high surface-to-volume ratios for surfficient active sites and induce molecule polarization through plasmon excitation as well. Herein we demonstrate one approach to fabricate nanoporous Au-Ag shell. Such material represents the dual functions serving as efficient catalysts and high-performance surface-enhanced Raman scattering (SERS) substrate. In-situ spectrum acquisition can track the conversion of p-nitrothiophenol to 4, 4'-dimercapto-azobenzene at ambient temperature...
August 7, 2017: Nanotechnology
Liang Ding, Juan Li, Ruiyu Jiang, Wei Song
Azobenzene-functionalized ABA triblock copolymers with controlled molecular weights are prepared first via a sequential ring-opening metathesis polymerization and acyclic diene metathesis polymerization in one-pot, which are readily converted, by a facile esterification, to the modified ABA triblock copolymers. Then, these reactive triblock copolymers can spontaneously self-assemble in a selective solvent to form reproducible and reversible polymeric core-shell nanoparticles. Finally, the stable and permanent shell-crosslinked nanoparticles are obtained by an intramolecular crosslinking reaction in dilute solution under UV light irradiation...
December 2, 2016: Materials
Michael S Scholz, James N Bull, Neville J A Coughlan, Eduardo Carrascosa, Brian D Adamson, Evan John Bieske
Due to their high photoisomerization efficiencies, azobenzenes and their functionalized derivatives are used in a broad range of molecular photoswitches. Here, the photochemical properties of the trans isomers of protonated azobenzene (ABH(+)) and protonated 4-aminoazobenzene (NABH(+)) cations are investigated in the gas phase using a tandem ion mobility spectrometer. Both cations display a strong photoisomerization response across their S1←S0 bands, with peaks in their photoisomerization yields at 435 nm and 525 nm, respectively, red-shifted with respect to the electronic absorption bands of the unprotonated AB and NAB molecules...
August 3, 2017: Journal of Physical Chemistry. A
Tiziana Benelli, Massimiliano Lanzi, Laura Mazzocchetti, Loris Giorgini
The chiroptical properties of amorphous chiral polymers functionalized with conjugated trans-azoaromatic chromophore linked to the backbone through a chiral cyclic pyrrolidine moiety of one single configuration at the solid state, as thin films, were investigated. For the first time nanometric thin films of amorphous polymers (not liquid crystals) showed a remarkable chiral amplification upon thermal treatment at a temperature close to their Tg. The side-chain azobenzene chromophores rearrangement driven by the enhanced chain mobility seems to favor the formation of nanodomains of conformationally ordered macromolecular chains with one prevailing helical handedness whose optical activity depends on the configuration of the intrinsic chirality of the monomeric units and which as a result are stable at room temperature for a long time...
August 1, 2017: Nanomaterials
Minoru Ishikawa, Takuya Ohzono, Takao Yamaguchi, Yasuo Norikane
We previously showed that disruption of intermolecular interactions, e.g., by lowering the molecular planarity and/or introducing bent structures, improves the aqueous solubility of compounds, and based upon that work, we hypothesized that azobenzene trans-to-cis photoswitching could also be utilized to enhance the aqueous solubility of compounds. Here, we demonstrate that UV/visible light irradiation can reversibly switch the aqueous solubilization of an anti-cancer candidate drug, a low-molecular-weight kinase inhibitor bearing an azobenzene moiety...
July 31, 2017: Scientific Reports
M Deiana, Z Pokladek, M Dudek, S G Mucha, L M Mazur, K Pawlik, P Mlynarz, M Samoc, K Matczyszyn
Three novel tyrosine-conjugated azobenzene molecules were designed and their ability to target a natural chiral host matrix (human serum albumin, HSA) was investigated. We found that the interplay between the spatial configuration of the chiral substituents and the change in local symmetry resulting from the photoisomerization process strongly affects the optical activity of the bound photochromes. In particular, the different signal amplification obtained upon binding of the photoswitches to the biopolymer enables obtaining a chirooptical system tunable over a wide range of wavelengths...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
Guido Angelini, Cristina Campestre, Luca Scotti, Carla Gasbarri
BMIM PF₆ (1-butyl-3-methylimidazolium hexafluorophosphate) and BMIM Tf₂N (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) are two conventional room-temperature ionic liquids widely employed and investigated as reaction media. Despite the presence of the same imidazolium ring in their structure they are different in many chemical and physical properties due to the nature of the anions. The thermal cis-trans isomerization of an electronically activated azobenzene have been used as reaction model to compare the behavior of PF₆(-) and Tf₂N(-)...
July 29, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Anemar Bruno Kanj, Kai Müller, Lars Heinke
Metal-organic frameworks (MOFs) are nanoporous, crystalline hybrid materials, which enable various functionalities by incorporating functional organic molecules. By using organic linker molecules that possess photoswitchable azobenzene side groups, the remote control over certain properties was introduced to MOFs. Different MOF materials in the form of powders and thin films have been used to demonstrate the photoswitching. The applications of these stimuli-responsive nanoporous solids range from switching the adsorption capacity of various gases over remote-controlled release of guest molecules to continuously tunable membrane separation of molecular mixtures...
July 31, 2017: Macromolecular Rapid Communications
Minwoo Kim, Ji-Hyeok Huh, Joohyun Lee, Hwi Je Woo, Kwangjin Kim, Dae-Woong Jung, Gi-Ra Yi, Mun Seok Jeong, Seungwoo Lee, Young Jae Song
We present a near-field mapping of electric fields from the individual superspherical and ultrasmooth gold nanoparticles (AuNPs) and artificially assembled AuNP nanostructures by measuring the reconfiguration of an azobenzene-containing polymer(azo-polymer) film. Various configurations of AuNPs and the azo-polymer were studied with atomic force microscopy measurements and calculations. The interference was systematically studied with AuNP dimers of various gap distances and different embedding depth in the polymer film...
July 31, 2017: Journal of Physical Chemistry Letters
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